Proteases are known to be present in plaque and saliva (indigeneous proteases), however, the origin (microbial or host) of these activities is unknown. In addition, the roles proteases might play in oral health and disease are similarly unproven. The immediate objectives of this research program are, (1) to characterize indigeneous proteases of plaque and saliva, (2) to determine the origin of indigeneous proteases, (3) to examine the sensitivity of some proteins of physiologic significance (IgA, C5, lysozyme, collagen) to degradation (inactivation) by indigeneous proteases, and (4) to compare the protease composition of periodontal disease-associated plaques with plaques from disease-free sites. Proteases indigeneous to dental plaque and saliva will be characterized by polyacrylamide gel electrophoretic examination of the patterns of degradation of a set of radiolabeled proteins. Proteases produced by oral bacteria cultivated in saliva and serum will be compared to the activities of plaque and saliva in an attempt to determine the specific origin of the indigeneous proteases. The long range goal of this study is to determine the roles proteases might play in oral inflammation and in modulating the microbial colonization of sites within the human oral cavity.